Peningkatan Performa Metode Steganografi Berbasis Difference Expansion Menggunakan Reduksi Selisih

Pertukaran data medis dilakukan untuk mempermudah profesional kesehatan untuk merawat pasien. Untuk hal itu, otentikasi menjadi perhatian utama untuk menjamin data medis yang bersangkutan adalah milik pasien yang benar dan juga berasal dari sumber yang benar. Salah satu metode yang dapat digunakan untuk keperluan tersebut adalah data hiding. Namun, metode yang digunakan tidak boleh menyebabkan distorsi yang permanen terhadap media yang digunakan karena dapat menyebabkan kesalahan diagnosa. Difference Expansion adalah satu metode yang mampu memenuhi persyaratan tersebut. Metode ini masih bisa menjadi topik yang menarik untuk diteliti. Khususnya pada kapasitas penyisipan data dan similarity antara cover image dengan stego image. Metode yang baik adalah metode yang mampu menyediakan kapasitas dan similarity citra yang tinggi. Pada penelitian ini, kami mengusulkan metode berbasis DE dengan berfokus pada dua masalah tersebut. Secara lebih terperinci, kami melakukan reduksi terhadap nilai selisih piksel agar menghasilkan tingkat similarity yang lebih baik dan mampu menyediakan kapasitas pesan yang lebih besar. Selain itu, kami menggunakan piksel median sebagai base point untuk menghitung selisih menggantikan piksel pertama pada masingmasing blok. Hasil percobaan yang dilakukan pada 5 citra medis menunjukkan bahwa metode yang diusulkan berhasil meningkatkan PSNR serta kapasitas penyisipan

Reversible watermarking scheme with image-independent embedding capacity

Permanent distortion is one of the main drawbacks of all the irreversible watermarking schemes. Attempts to recover the original signal after the signal passing the authentication process are being made starting just a few years ago. Some common problems, such as salt-and-pepper artefacts owing to intensity wraparound and low embedding capacity, can now be resolved. However, some significant problems remain unsolved. First, the embedding capacity is signal-dependent, i.e., capacity varies significantly depending on the nature of the host signal. The direct impact of this is compromised security for signals with low capacity. Some signals may be even non-embeddable. Secondly, while seriously tackled in irreversible watermarking schemes, the well-known problem of block-wise dependence, which opens a security gap for the vector quantisation attack and transplantation attack, are not addressed by researchers of the reversible schemes. This work proposes a reversible watermarking scheme with near-constant signal-independent embedding capacity and immunity to the vector quantisation attack and transplantation attack

Reversible Data Hiding pada Audio Digital Berbasis Difference Expansion

Metode penyisipan data pada media lain berkembang dengan pesat beberapa tahun terakhir, skema penyisipan data secara konensional dapat menyebabkan kerusakan secara permanen (irreversible) setelah preses ekstraksi pada media penyisipannya. Dalam beberapa aplikasi seperti diagnosis medis, penegakan hukum, dan militer, mengembalikan media penyisipannya menjadi media asli setelah proses ekstraksi data merupakan hal penting, skema penyisipan data yang dapat menangani kasus seperti ini disebut reversible. Difference expansion adalah salah satu skema reversible data hidingyang sederhana dan mudah diimplementasikan. Dalam penelitian ini kami mengusulkan penyisipan data pada media audio menggunakan skema reversible data hiding berbasis difference expansion yang berfokus pada peningkatan kapasitas penyisipan dan kualitas media-carrier setelah proses penyisipan dengan mereduksi nilai selisih data dengan skema Improve Reduce Difference Expansion (IRDE) . Skema yang diusulkan telah di evaluasi dengan tiga file audio WAV dengan jenis yang berbeda. Hasil penelitian menunjukkan bahwa, skema yang diusulkan memiliki kapasitas dan kualitas audio yang baik

Reversible Data Hiding Using Hybrid Method of Difference Expansion on Medical Image

Data hiding in the image can cause permanent distortion (irreversible), in other applications such as medical images, distortion can cause misdiagnosis. To overcome these problems, a special scheme is required for the embedding data on medical image. Reversible data hiding is a scheme that can restore the image to original image without distortion after the embedded information is extracted. Difference Expansion (DE) is one of the schemes in reversible data hiding that is simple and easy to implement. In this paper, we propose two schemes based a hybrid combination of DE to increase on capacity and visual quality. Medical image has characteristics is the large of smooth block areas, in which DE method is applied to the non-smooth areas image. We used four different medical images to evaluate the proposed scheme. The results showed that the proposed scheme has a high capacity and better visual quality than the original scheme and similar schemes have been proposed previously. Embedding capacity of the proposed scheme is up to 0.66 bpp with visual quality of PSNR value is up to 48 dB

Reversible Data Hiding Exploiting Variance in Wavelet Coefficients

In this paper, we present a new reversible data hiding scheme that utilizes the wavelet transform and better exploits the large wavelet coefficient variance to achieve high capacity and imperceptible embedding. Our scheme differs from those of previous studies in that the wavelet coefficients histogram rather than the gray-level histogram is manipulated. In addition, we design intelligent histogram-shifting rules to avoid the decimal problem in grayscale pixel values after recovery process to achieve reversibility. Small changes in the wavelet coefficients after embedding process are important factors contributing to low visual distortion in the marked image. Furthermore, an important property of our scheme is that the use of threshold differs greatly from previous schemes. The experimental results show that our scheme outperforms other reversible data hiding schemes.Facultad de Informátic

ROI-based reversible watermarking scheme for ensuring the integrity and authenticity of DICOM MR images

Reversible and imperceptible watermarking is recognized as a robust approach to confirm the integrity and authenticity of medical images and to verify that alterations can be detected and tracked back. In this paper, a novel blind reversible watermarking approach is presented to detect intentional and unintentional changes within brain Magnetic Resonance (MR) images. The scheme segments images into two parts; the Region of Interest (ROI) and the Region of Non Interest (RONI). Watermark data is encoded into the ROI using reversible watermarking based on the Difference Expansion (DE) technique. Experimental results show that the proposed method, whilst fully reversible, can also realize a watermarked image with low degradation for reasonable and controllable embedding capacity. This is fulfilled by concealing the data into ‘smooth’ regions inside the ROI and through the elimination of the large location map required for extracting the watermark and retrieving the original image. Our scheme delivers highly imperceptible watermarked images, at 92.18-99.94dB Peak Signal to Noise Ratio (PSNR) evaluated through implementing a clinical trial based on relative Visual Grading Analysis (relative VGA). This trial defines the level of modification that can be applied to medical images without perceptual distortion. This compares favorably to outcomes reported under current state-of-art techniques. Integrity and authenticity of medical images are also ensured through detecting subsequent changes enacted on the watermarked images. This enhanced security measure, therefore, enables the detection of image manipulations, by an imperceptible approach, that may establish increased trust in the digital medical workflow

Assessment of perceptual distortion boundary through applying reversible watermarking to brain MR images

The digital medical workflow faces many circumstances in which the images can be manipulated during viewing, extracting and exchanging. Reversible and imperceptible watermarking approaches have the potential to enhance trust within the medical imaging pipeline through ensuring the authenticity and integrity of the images to confirm that the changes can be detected and tracked. This study concentrates on the imperceptibility issue. Unlike reversibility, for which an objective assessment can be easily made, imperceptibility is a factor of human cognition that needs to be evaluated within the human context. By defining a perceptual boundary of detecting the modification, this study enables the formation of objective guidelines for the method of data encoding and level of image/pixel modification that translates to a specific watermark magnitude. This study implements a relative Visual Grading Analysis (VGA) evaluation of 117 brain MR images (8 original and 109 watermarked), modified by varying techniques and magnitude of image/pixel modification to determine where this perceptual boundary exists and relate the point at which change becomes noticeable to the objective measures of the image fidelity evaluation. The outcomes of the visual assessment were linked to the images Peak Signal to Noise Ratio (PSNR) values, thereby identifying the visual degradation threshold. The results suggest that, for watermarking applications, if a watermark is applied to the 512x512 pixel (16 bpp grayscale) images used in the study, a subsequent assessment of PSNR=82dB or greater would mean that there would be no reason to suspect that the watermark would be visually detectable. Keywords: Medical imaging; DICOM; Reversible Watermarking; Imperceptibility; Image Quality; Visual Grading Analysis